When you collect data, you can try to collect it from everyone in the group …
or you can use a subset, or sample, of the population.
Decisions about sampling usually depend on the purpose of the evaluation, the questions you are asking, the size of the population, and the methods you are using to collect information.
- Will you use a sample or include the whole population?
- If you do sample, what type of sample will you use?
- Do you need to be able to generalize your findings to the whole population?
- What size will your sample be?
It is not our intent in this section to cover all aspects of research design and evaluation. We suggest you access other resources to help select an appropriate sample.